#include <stdlib.h>
#include <stdio.h>

int main() {
  int n;
  float soma, termo;

  n = 2;
  soma = 0;
  termo = 1/(float)n;
  soma = soma + termo;
  n++;
  termo = 1/(float)n;
  soma = soma + termo;
  n++;
  termo = 1/(float)n;
  soma = soma + termo;

  printf ("%f", soma);

  return 0;
}

